Escherichia coli is associated with a wide variety of intestinal diseases in human and in animals. Some pathogenic E. coli produces attaching and effacing (A/E) lesions, characterized by intimate bacterial adherence to enterocytes and disruption of the underlying cytoskeleton. Such isolates have been termed A/E E. coli (AEEC).
Reports have shown that A/E lesions are characteristic of enteric pathogens of humans such as enteropathogenic E. coli (EPEC) responsible for severe childhood diarrhea in the developing countries, and enterohemorrhagic E. coli (EHEC) causing hemorrhagic colitis and hemolytic uremic syndrome (HUS). A/E lesions have also been associated with diarrhea in different animal species such as rabbits, calves, dogs, cats, lambs, and pigs.
A/E lesions result from the intimate bacterial adherence to the apical surface of the enterocytes and activation of several chromosomal gene products that interact with components of the host cell. Such gene products are commonly called AEEC virulence-associated proteins. Examples of these virulence-associated proteins are the intimin (Eae) and the secreted proteins Tir (translocated intimin receptor), EspA, EspD, and EspB.
Currently, the only approach to the control and treatment of AEEC-associated diseases is the use of antibiotics, an approach which is becoming less and less desirable due to problems of bacterial resistance and antibiotic residues. Therefore, alternative approaches to control post-weaning diarrhea must be sought.
Alternatively, another approach known in the art suggests the use of AEEC virulence-associated proteins as antigens to immunize an animal in order to stimulate antibody production against the related pathogen. However, no indication of the efficacy of this approach has been shown to prevent AEEC infection in a mammal. Examples of such an alternative approach are shown in U.S. Pat. No. 6,204,004 and in international patent applications WO 99/41614; WO 97/40063 and WO 99/24576.
Also known in the art is the use of avian antibodies (IgY) in passive immunization. For instance, WO 00/52055 discloses the use of specific egg yolk IgY antibodies for immunotherapy in animal breeding and animal production. It also discloses the use of IgY antibodies in kits for diagnostics.
U.S. Pat. No. 5,932,250 is directed to the treatment of vascular disorders particularly arteriosclerosis and atherosclerosis in warm-blooded animals. More specifically, this U.S. patent discloses methods of controlling cholesterol levels, lipid deposits, and the development of atheromatous lesions in warm-blooded animals by the ingestion of egg products containing IgY antibodies raised against Escherichia coli proteins.
U.S. Pat. No. 6,162,441 discloses a method for producing anti-E. coli 0157 IgY antibodies in egg-laying hens.
The problem with WO 00/52055, U.S. Pat. Nos. 5,932,250 and 6,162,441 is that the in vivo efficacy of the IgY produced has not been demonstrated. Indeed, none of these contain evidence with respect to the feasibility of an approach consisting of administering to a mammal, an antibody immunologically specific for an AEEC virulence-associated protein for preventing an in vivo AEEC intestinal infection. Therefore, there is still a need for antibodies, egg products and methods for the prevention or treatment of AEEC-mediated diseases.